Everyday Noise Levels May Affect the Heart

THURSDAY, May 9 (HealthDay News) -- Even the minor noise that
fills everyday life, from the ring of a cell phone to the
conversation that follows, may have short-term effects on heart
function, a small new study suggests.

In the study of 110 adults equipped with portable heart
monitors, researchers found that people's heart rate tended to
climb as their noise exposure increased -- even when the noise
remained below 65 decibels. That's about as loud as a normal
conversation or laughter.

There was also a negative impact on people's heart rate
"variability" -- a measure of the heart's adaptation to what is
going on around you. Greater variability in the interval between
heartbeats is better. When people are relaxed, the space between
heartbeats is usually a bit longer as they exhale, and shorter as
they inhale.

When people are stressed, however, some of that natural
variation is lost. And studies have linked lesser heart rate
variability to an increased risk of heart attack.

So does all of this mean you need to wear earplugs to protect
your heart? Probably not, experts say.

For any one person, the effects of everyday noise on heart
function may be small, said Charlotta Eriksson, a researcher at the
Karolinska Institute, in Stockholm, Sweden. Eriksson was not
involved in the study.

But since we are all exposed to noise, even a minor effect on
heart health could be important on the broad "population level,"
said Eriksson, who has studied the effects of loud traffic -- from
roads or airports -- on people's blood pressure and heart
function.

Research has consistently found links between loud workplaces
and an increased risk of heart disease, said Dr. Wenqi Gan, a
researcher at North Shore-LIJ Health System's Feinstein Institute
for Medical Research, in Manhasset, N.Y.

The evidence is more mixed when it comes to "community noise,"
like traffic sounds, said Gan, whose own research has found a
connection.

He said the mixed results may be because it's difficult to weed
out the effects of community noise on individuals. You might live
in a noisy section of a big city, but have good, sound-muffling
windows, for example.

"And some people are more sensitive to noise than others," Gan said. If noise affects the heart by stressing people out, he said, then your personal sensitivity to it would be important.

The new findings, reported in the May issue of the journal
Environmental Health Perspectives, are based on 110 adults
who wore portable devices that measured their heart activity and
noise exposure during their normal daily routines.

What was "interesting," Eriksson said, is that lower-level noise
seemed to curb activity in the parasympathetic nervous system --
the branch of the nervous system that acts as a "brake," lowering
heart rate and relaxing the blood vessels, for example.

Louder noise, meanwhile, seemed to rev up the sympathetic
nervous system -- the branch that boosts heart rate, constricts
blood vessels and otherwise sends us into "fight or flight"
mode.

The value of the findings is that they suggest a biological
reason for why noise has been linked to ill heart effects, said
Alexandra Schneider, one of the researchers in the Institute of
Epidemiology at Helmholtz Zentrum Munchen, in Germany, who worked
on the study.

"Our main focus was to find a possible mechanism that could be responsible for the observed health effects in other studies," Schneider said.

The study was not designed to offer people advice on how much
noise is "bad" for their hearts, she said.

Gan agreed. "This study is a first step in exploring the
underlying biological mechanisms for the association between noise
exposure and cardiovascular disease," he said. "We need more
studies like this."

A big question, said study author Schneider, is whether the
short-term effects of noise, repeated over time, ultimately affect
heart health -- particularly for people who already have chronic
medical conditions.

Although the study tied increased noise exposure to a rise in
heart rate, it did not establish a cause-and-effect
relationship.

More information

The U.S. Environmental Protection Agency has more information on
noise
pollution.

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.